Cash carried must be declared when entering or leaving the European Union (EU). Use the “Cash Declaration” form to declare cash.
Duty to Declare Cash Carried when Entering or Leaving the European Union (EU)
In the Federal Republic of Germany, the cash must be declared in writing to the customs office responsible for the border crossing where you enter or leave the EU. The “Declaration of Cash/Funds” form is available at customs offices.
More information can be found on the website of the German Customs Office.